Conventionally, a method of generating a three-dimensional image of an object using a group of a series of tomographic images scanned by, for example, an X-ray CT (computed tomography) apparatus, an MRI (magnetic resonance imaging) apparatus, or an ultrasonic diagnostic apparatus is known. For example, PTL 1 discloses an image display device that generates and displays an inside-out image, which is obtained when the inside surface of an organ is turned over to the outer surface, by extracting the contour of a hollow organ from a medical image constructed by scanning the hollow organ, setting a radial line from the radiation center set inside the hollow organ towards the contour of the lumen, and copying a pixel value of a point inside the hollow organ onto the radial line outside a contour point.
In addition, PTL 2 discloses a three-dimensional image construction method capable of checking the irregularities inside an object from the outside by generating a two-dimensional image by a perspective transformation of a volume image, which is formed by stacking tomographic images of the object, to a coordinate system on an arbitrary perspective plane, calculating a distance between a position of a virtual linear light source set inside the object and an inside contour point of the object, and reflecting the distance in the shading of the two-dimensional image. In addition, PTL 3 discloses a medical image processing device that displays an image, which has a central portion in which a virtual endoscopic image equivalent to an image observed with an endoscope is displayed and a peripheral portion in which the inside of a hollow organ is spread, for example, by setting a viewpoint inside the hollow organ and setting the projection directions in different directions in the central portion and the peripheral portion of a projection plane.